SsangYong Musso. Manual - part 138

1F-136 ENGINE CONTROLS

SSANGYONG Y158

Circuit Description

When the vehicle is first started, it operates in Open
Loop, ignoring the oxygen sensor signal and calculating
the fuel/air ratio based on inputs from the Engine Cool-
ant Temperature (ECT), Throttle Position (TP), and
Manifold Absolute Pressure (MAP) sensors only. The
Engine Control Module (ECM) will begin using the oxy-
gen sensor signal for controlling fuel delivery (Closed
Loop) when the following conditions are met:

•••••

The engine has run a minimum amount of time based
on ECT at engine start up.

•••••

The oxygen sensor has a varying voltage output
showing that it is hot enough to operate properly.

•••••

The ECT has increased a minimum amount based
on ECT at engine start up.

Conditions for Setting the DTC

•••••

Start-up engine temperature is greater than
-40 °C (-40 °F).

•••••

Air temperature is greater than -40 °C (-40 °F).

•••••

P0116, P0117, and P0118 are not set.

Action Taken When the DTC Sets

•••••

The Malfunction Indicator Lamp (MIL) will illuminate
after two consecutive driving cycles in which the diag-
nostic runs with the fault active.

•••••

The ECM will record operating conditions at the time
the diagnostic fails. This information will be stored in
the Freeze Frame and Failure Records buffers.

•••••

A history DTC is stored.

DIAGNOSTIC TROUBLE CODE (DTC) P0125

ENGINE COOLANT TEMPERATURE WARM-UP

Conditions for Clearing the MIL/DTC

•••••

The MIL will turn off after three consecutive driving
cycles in which the diagnostic runs without a fault.

•••••

A history DTC will clear after 40 consecutive warm-
up cycles without a fault.

•••••

The DTC(s) can be cleared using the scan tool.

Diagnostic Aids

When DTC P0125 is set, a skewed ECT sensor or a
stuck open thermostat is indicated.

An intermittent may be caused by a poor connection,
rubbed-through wire insulation or a wire broken inside
the insulation.

Check for a poor connection or damaged ECM harness.
Inspect the ECT sensor signal circuit and ground circuit
terminals for the following conditions:

•••••

Improperly mating.

•••••

Broken locks.

•••••

Improperly formed.

•••••

Damaged terminals.

•••••

Poor terminal-to-wire connection.

•••••

Damaged harness.

Perform an intermittent test. If the connections and the
harness check OK, monitor a Digital Voltmeter (DVM)
connected between ECT sensor signal circuit and ground
circuit terminals while moving the related connectors
and the wiring harness. If a fault is induced, the
resistance reading will change. This may help to isolate
the location of the malfunction.

YAA1F600

ENGINE CONTROLS 1F-137

SSANGYONG Y158

Use the Temperature vs. Resistance Values table to
evaluate the possibility of a skewed sensor. Refer to
“ Temperature vs. Resistance” in this section.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Table.

1. The Euro On-Board Diagnostic (EOBD) System

Check prompts the technician to complete some
basic checks and store the freeze frame and failure

records data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.

10. The replacement ECM must be reprogrammed. Re-

fer to the latest Techline procedure for ECM repro-
gramming.

Step

Action

Value(s)

Yes

DTC P0125 Engine Coolant Temperature Warm-Up

Perform an Euro On-Board Diagnostic (EOBD) System
Check.
Is the system check complete?

1. Allow the engine to cool fully to ambient

temperature.

2. Turn the ignition switch ON, with the engine OFF and

install a scan tool.

3. Compare the Engine Coolant Temperature (ECT)

sensor reading to the Intake Air Temperature (IAT)
sensor readings.

Are the temperature readings close?
1. Turn the ignition OFF.
2. Disconnect the ECT sensor electrical connector.
3. Turn the ignition ON, engine OFF.
4. Using a Digital Voltmeter (DVM), measure the

resistance across the ECT sensor terminals 1 and 4.

5. Check the ECT sensor value to actual coolant

temperature vs. Resistance table.

Does the ECT sensor accurately reflect the actual
engine coolant temperature?
1. Turn the ignition OFF.
2. Disconnect the ECT sensor electrical connector.
3. Turn the ignition ON.
Is the ECT sensor value near the specified value?
Jumper the ECT sensor signal circuit terminal 1 and the
sensor ground circuit terminal 4 together at the ECT
sensor connector.
Is the ECT sensor value near the specified value?
Check for proper cooling system operation
And repair as necessary.
Is the repair complete?
Check the ECT sensor electrical connector
Terminals 4 and 1 and Engine Control Module (ECM)
electrical connector terminals 78 and 79 for poor
connectors or malfunctioning terminals and repair as
necessary.
Is the repair complete?

Go to Step 2

Go to “Euro

On-Board

Diagnostic

System Check”

Go to Step 4

Go to Step 3

Go to Step 4

Go to Step 11

4.9 v

Go to Step 5

Go to Step 8

0 v

Go to Step 6

Go to Step 7

Go to Step 12

Go to

“Diagnostic

Aids”

Go to Step 12

Go to Step 8

1F-138 ENGINE CONTROLS

SSANGYONG Y158

Check the ECT sensor signal circuit for an open or short
to ground and repair as necessary.
Is a repair complete?
Check the ECT sensor ground circuit for an open and
repair as necessary.
Is a repair complete?
1. Turn the ignition OFF.
2. Replace the ECM.
Is the action complete?
Replace the ECT sensor.
Is the action complete?
1. Using the scan tool, clear the Diagnostic Trouble

Codes (DTCs).

2. Start the engine and idle at normal operating

temperature.

3. Operate the vehicle within the conditions for setting

this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and
passed?
Check if any DTCs are set.
Are any DTCs displayed that have not been diagnosed?

Step

Action

Value(s)

Yes

DTC P0125 Engine Coolant Temperature Warm-Up (Cont’d)

Go to

applicable

DTC table

System OK

Go to Step 13

Go to Step 2

Go to Step 12

Go to Step 10

Go to Step 12

Go to Step 9

ENGINE CONTROLS 1F-139

SSANGYONG Y158

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